Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

It's likely that you can trigger avalanches in recently wind-drifted snow on Friday. Watch for signs of active wind transport, feel for denser, heavier snow underfoot, and look for textured or pillow-like surfaces. If you find fresh drifts, notice long shooting cracks from your weight, or see recent avalanches, avoid steep slopes nearby.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Newly formed wind slabs are where you can expect most avalanche activity to occur on Friday. As you climb higher, more wind-effect will result in larger and more reactive avalanches. Drifts, especially by the end of the day, could be 2 or more feet deep. 

    An observer reported new snow was well-bonded to the crust that formed due to rain on Christmas Eve at least through mid elevations, but subsequently froze. We're not sure if snow is well-bonded to the crust everywhere. You can check with pole or hand pits to see how well the snow sticks to the underlying crust as you travel. If snow slides easily on the crust, you'll want to take a more conservative approach and avoid all steep terrain. 

    It's working in our favor that temperature trends are dropping, so snow should remain "right side up" in non wind-loaded areas, unless the layer doesn't stick to the underlying crust. Use small test slopes and search for drifted snow around terrain features, in gullies, and along ridgelines. Steer around these areas in steep terrain. 

    Example photo: If you encounter cracking, small reactive slabs, or natural avalanches, it's time to reevaluate and stick to mellow terrain. Note the slightly textured surface in this photo- similar to Friday, there will be soft wind-drifted slabs, like what you see in this photo. 

    Photo: Julz Holder - Grounding Truth

Avalanche Discussion

About 4 inches of snow fell Thursday afternoon, and we could get six inches or more of snow overnight, and then similar amounts during the day. Wind will be strongest in the morning, redistributing new snow. As more snow falls throughout the day, the slabs could be hidden by non wind-affected snow. 

On Christmas Eve, we had rain reaching up to nearly the top of the mid-elevation band. This resulted in a crust on Christmas Day, and continuously cooling temperatures since then has only further frozen any previously wet snow. When rain fell down low, heavy snow likely fell at upper elevations and was subsequently highly wind-affected. We expect most of these slabs would have stabilized over the last few days, but it's not out of the question that an avalanche might fail deeper than expected, or step down to a deeper layer if you trigger a smaller slab. 

Snowfall varies widely throughout the zone. I was in the Baker backcountry on Monday and, on average, found 6ft of snow at 4800ft. At the same elevation in Canyon Creek, there was closer to 4ft of snow. You can see similar structures in pits, yet different snow depths in the photos from earlier in the week in the media gallery. Due to the recent flooding, some roads are still closed, and a few commonly used locations are no longer accessible. 

State and local resources are working diligently to reduce the impacts of destructive storms that occurred earlier this month. We can help by respecting affected communities, complying with road closures, and adhering to ski area uphill travel policies.

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